The story in all three seasons pits Stella Gibson, brought into Belfast to investigate serial killings done by Paul Spector, who seems like the sweetest guy in the world. Both parts are played to perfection - by Gillian Anderson and Jamie Dornan - and Anderson's performance is one of the most powerful I've ever seen on any television or movie screen.
There's plenty of action, but what makes this series special are the deeper moments of contemplation and reflection. Gibson nails her suspects, at last, at the end of the second season, but the match of wits continues and escalates in the third season, as Spector evinces amnesia, presumably brought on by the trauma of his capture, which nearly kills him.
Is he feigning or really suffering a memory loss, which would make his prosecution in court much more difficult. Gibson is sure he's feigning, the medical and psychology staff - and we the audience - are not so sure.
The doctors in intensive care, Spector's nurse in particular, are correctly devoted to bringing this monster back to full health. The head of psychiatric facility to he's brought wants only to find the truth of what's going on now in Spector's brain.
This of course is connected to what went on in his brain before. I've seen many examinations of the homicidal mind on television and in cinema over the decades, but never as breathtakingly chilling as in this third season of The Fall. It's a trip that Joseph Conrad, who explored insanity in a different context in Heart of Darkness, would have enjoyed, if that's the right word.
Spector's outburst - in which he physically beats Gibson after an interrogation which puts him in a corner and strips his soul bare (the police have linked him to a killing which took place before his amnesia-blanked years) - is both shocking and instantly totally believable in retrospect, a winning combination in a narrative moment. Not so believable is why Spector would not have been put in a padded cell somewhere after that, rather than back to the psychiatric unit where he does even more damage, and that's the biggest flaw in in this otherwise flawless story. But that story is so riveting and convincing and horrifying that it easily survives as a masterpiece despite the flaw.
Word on the web is that Stella Gibson may well return in a 4th series created, written, and directed by Allan Cubitt. The supporting characters - such as Spector's attorney Aidan McCardle (Loxley on Mr. Selfridge) - are excellent. I'll be watching for sure.